In this condition, which is only exceptionally interrupted by a brief return of the reflexes and of a clouded consciousness, and even more rarely ends in recovery, the patient remains for from twenty four to forty-eight hours, seldom longer. Then conies death preceded by a further depression of the temperature and by a gradual diminu tion in the number and depth of the respiratory movements. Ex amination of the brain post mortem shows the presence of no lesions to account for this. condition.
Frerichs saw 250 fatal cases of diabetes out of a total of 400, and of this number coma was the cause of death in 151; other statistics show a much smaller proportion. Coma may terminate any case, whatever its degree of severity, yet patients with obstinate glycosuria are in very much greater danger of this complication than are those in whom the glycosuria yields readily to appropriate treatment. Most cases occur in patients between twenty and forty years of age.
The cause of the coma is often impossible to determine. The patients are surprised by it without any unusual objective or sub jective symptoms having given warning of its approach. The occa sional exceptions to this rule in the shape of acute intestinal catarrh or obstinate constipation have already been mentioned (page 105). More frequently the attack is preceded by severe bodily exertion, excesses in baccho et venue, intellectual overwork, or mental excite ment. The numerous exact and indisputable observations on this point suggest the thought that we may not always have to deal with coma as a " specific diabetic intoxication" (Frerichs); they would. in dicate that coma may be often only the expression and the result of a condition of extreme nervous exhaustion. The central nervous sys tem of a poorly nourished diabetic works evidently without any available reserve force. Every weakening movement, every over exertion brings paralysis in its train and gives rise to a condition similar to that resulting from an acute cerebral hemorrhage (apoplectic coma). There is nothing of special significance in the coexistence of marked acetonuria and diaceturia, for they but give expression to the character of the primary disease; it would be remarkable if they were absent.. There need be as little question of a peculiar intoxication here as there is in apoplectic cases. It is natural enough that the apoplectic should frequently recover from the shock to the central nervous system, while the diabetic does not. The former is essen
tially endowed with powers of resistance, the latter is a greatly weak ened person. But it is not intended to deny by this that there arc forms of coma referable to a genuine diabetic intoxication. Those eases especially belong to this category in which for a long period there has been an excretion of oxybutyric acid.
3. Brain and Spinal Cord.",—a. Symptoms without Central Le sion.—In certain rare cases of diabetes we encounter symptoms which we are accustomed to refer to disease of the central nervous system, such as hemiplegia, aphasia, hemianopsia, and localized convulsions (resembling those of Jacksonian epilepsy). These disturbances may subside or they may lead to a fatal issue. But in the latter case the post-mortem examination reveals no central lesion and no disease, or at most a very insignificant one, of the vessels. The cases recall certain rare forms of urfemia, the phenomena of encephalopathia saturnina, the paralyses without anatomical lesion found in pellagra, etc., and appear to be of toxic origin. Lepine and Redlich have re ported cases which may be cited as examples of this condition.
b. Central Lesions.—Diseases of the brain and spinal cord due to a central lesion or system diseases are hardly ever immediately de pendent upon diabetes. If they coexist with diabetes it may be that they play a causative role or they may be entirely unconnected with it. An indirect relation between diabetes and such affections may be traced in several ways : (1) Through the establishing of an hereditary predisposition, for diabetes has a certain predilection for individuals with a neuropathic taint; (2) through the intervention of disease of the vessels excited directly or indirectly by diabetes (see p. 109), and leading finally to hemorrhage, softening, etc. Many instances of this sort are recorded in the literature of diabetes; (3) through the agency of syphilis. We have shown that syphilis may under certain circum stances stand iu a causal relation to diabetes, and we know ou the other hand what an important part syphilis may play in the produc tion of diseases of the brain and spinal cord; (4) through infectious diseases whose occurrence is favored by diabetes, and in the course of which metastases may take place from the local foci of disease to the brain (tuberculosis, suppuration, aphthous stomatitis).